The Center for Clinical Epidemiology and Biostatistics (CCEB) and the Cancer Center at the University of Pennsylvania submit this request for the renewal of an innovative research training program for postdoctoral training in Cancer Clinical Epidemiology, specifically designed to strengthen the links among traditional epidemiology, clinical oncology, and the basic sciences. The objective of the program is to train individuals to be rigorous and independent academic investigators able to use the range of approaches available in epidemiology to address research issues in cancer etiology, prognosis, prevention and early detection, treatment, or clinical economics of cancer. In the renewal of this research training program, the CCEB and the Cancer Center have expanded the existing training program, which originally was designed solely for clinicians to receive additional training in clinical epidemiology. The training program now offers training in genetic and molecular epidemiology to postdoctoral level basic scientists, as well. The training program includes two pathways. Pathway 1 is a 2 to 3 year training program consisting of required courses in clinical epidemiology, research methodology, and biostatistics; elective courses; extensive independent readings; attendance at and participation in research seminars at the CCEB; plus the completion of an independent research project. Trainees in this pathway are candidates for a Master of Science in Clinical Epidemiology (M.S.C.E.) degree upon completion. This is a continuation of the training the CCEB has been offering for 10 years to clinicians. In this award cycle, very selected individuals with a Ph.D. in molecular biology or the equivalent who desire training in cancer molecular or genetic epidemiology will also be eligible to participate in this 2 to 3 year training program in epidemiologic methods. Pathway 2 provides a 2-year postdoctoral training experience for nonclinicians who already have a Ph.D. in epidemiology who wish to pursue an academic research career in cancer genetic or molecular epidemiology. These trainees will participate in a laboratory-based training program, supplemented by cancer genetic or molecular epidemiology course work. Pathway 2 also includes the completion of an independent research project in cancer genetic or molecular epidemiology. For all trainees, this program: (1) provides in-depth knowledge of the research techniques appropriate to clinical epidemiologic research or enhances skills received in prior training; (2) provides research experience with mentors in clinical epidemiology and cancer research; and (3) brings together faculty and fellows through participation in seminar series in the CCEB and the Cancer Center. Strengths of the program are the long history of successful research training programs in clinical epidemiology, cancer, and genetics at the University of Pennsylvania and, specifically, offered by the CCEB and the Cancer Center; the collaborative links between the two Centers; and the comprehensive course offerings and research programs that are available to trainees.